In an information recording/reproducing apparatus for recording data onto an information recording medium, for example, such as an optical disc, the optimum power of a recording power is set by an OPC (Optimum Power Control) process in accordance with the type of the optical disc, the type of the information recording/reproducing apparatus, a recording speed, or the like. In other words, the recording power is calibrated. This can realize an appropriate recording operation in response to variations in property of the information recording surface of the optical disc, or the like. For example, when the optical disc is loaded and a writing command is inputted, the light intensity of a recording laser beam is changed sequentially and gradually, and OPC data is recorded into an OPC area; namely, a so-called test-writing process is performed. After that, the OPC data recorded in this manner is reproduced, and this reproduction result is judged by a predetermined evaluation criterion to obtain the calibration value (e.g. optimum recording power) of the recording power.
Moreover, the OPC that is simultaneously performed with the actual recording operation (i.e. running OPC) also allows the setting of the optimum recording power associated with the recording laser beam.    Patent document 1: Japanese Patent No. 3159454